This invention relates to a scraper-chain conveyor having first and second straight portions joined by a curved portion.
A scraper-chain conveyor of this construction is used to convey won mineral material from a longwall face directly into the roadway at the "downstream" end of the longwall working. In order to guide the scrapers of the conveyor round the curved conveyor portion, it is standard practice to use a special type of guide assembly positioned at the inside of the curve. Such a guide assembly usually has a pair of pulley wheels which are independently rotatable about a vertical axis. The diameter of each of the pulley wheels is the same as that of the inside of the curved conveyor portion, and the rims of the pulley wheels engage the adjacent ends of the scrapers. (See Gluckauf, 1976, pages 873 to 877; DE-PS 20 65 424; DE-PS 20 51 384).
Unfortunately, the scraper assembly can only be adequately guided by such an assembly, if at least four scrapers are always in engagement with each of the pulley wheels. This means that the scrapers must be fitted relatively closely together on their drive chain or chains. Another disadvantage of this type of guide assembly is that its large dimensions make it difficult to move under the roof of the mine working in the critical region where the longwall face meets the roadway. A further disadvantage is that, in order to take up the very large forces arising from the tension in the drive chain(s) in the region of the curved conveyor portion, the entire guide assembly must be of a very robust and stable construction. This results in a very heavy and bulky unit. As the guide assembly has to be advanced together with the conveyor (to follow up the advance of the face) this results in the advance of the conveyor being unduly difficult and complicated.
The aim of the invention is to provide a conveyor of the initially stated type which can be used without a guide assembly, or with a guide assembly of relatively light construction.